The present invention relates to leak-resistant battery modules for battery-powered devices and, more particularly, to a field-replaceable battery module for an battery-powered rifle accessory such as a telescopic scope of the type including an electrically-powered illuminated reticle.
Battery-powered aiming devices such as rifle scopes, range finders, and night-vision equipment, for example, are designed to be mounted to a firearm for use by a shooter. Modern versions of these devices often include a battery compartment for receiving an electric storage battery (such as an AA- or AAA-size battery) that supplies power to an electronic component of the device. Typical battery compartments include two or more electrical contacts positioned so that they contact respective positive and negative terminals of the battery. One of the electrical contacts is typically spring biased or resilient so that the contacts press against and form an electrical connection with the battery terminals. However, the spring force and resiliency of such contacts is often insufficient to prevent interruption of the supply of power from the battery to the device when exposed to recoil forces of the firearm.
Battery compartments of some battery-powered devices include a conductive housing that completes a circuit between the battery terminals. A conductive housing of this type can corrode as a result of an electrolytic reaction induced by prolonged exposure to battery voltage. If the conductive housing is integral with the battery-powered device, then corrosion can cause serious damage to the device. This is of special concern with aiming devices, which house delicate optical and electronic components. Batteries can also rupture or leak, spilling corrosive chemicals onto the battery compartment and other parts of the device, which can result in similar damage.
Thus, there exists a need for an improved method and apparatus for using electric storage batteries with battery-powered aiming devices and other battery-powered devices generally.
In accordance with the present invention, a replaceable battery module is provided for use with a battery-powered device. The battery module includes a canister sized to receive an electric storage battery, such as a commercially available lead-acid, alkaline, nickel-cadmium, lithium, or other rechargeable or non-rechargeable battery. An aperture is formed in the canister in a position such that a first one of the battery""s terminals is positioned proximal of the aperture when the battery is installed in the canister. The battery module further includes a conductive contact positioned to extend through the aperture and including a battery-contacting end for contacting the first battery terminal. A seal is positioned between the canister and the contact for sealing the aperture.
Many commercially available batteries, such as AA-size, AAA-size, N-size, and ⅓N-size batteries, are cylindrical in shape, having a positive terminal at one end and a negative terminal at the other end. However, other batteries, such as 9-volt transistor batteries, for example, are non-cylindrical and have terminals that are both located at a single end of the battery. The present invention may be used with any electric storage battery, but is particularly useful with cylindrically shaped batteries having positive and negative terminals at opposite ends. Accordingly, the canister may be conductive and adapted to be placed in electrical communication with a second one of the battery terminals when the battery is installed in the canister. The canister thereby provides a conductive path that allows both the positive and negative battery terminals to be accessed at one end of the battery module. This arrangement prevents electrolytic corrosion of the battery-powered device as has been problematic in prior art battery-powered devices, in which a housing of the device provides the conductive path. Alternatively, a second conductive contact may be provided for contacting the second one of the battery terminals, in which event it is unnecessary for the canister to be conductive.
To prevent corrosion caused by accidental battery leakage, the canister, the conductive contact (or contacts), and the seal preferably form a sealed chamber that fully encloses the battery. The sealed chamber may have a liquid impermeable seal, a gas-tight seal, a hermetic seal (both liquid and gas-tight), or a solids impermeable seal. To relieve pressure caused by outgassing of the battery, the battery module may include a pressure release valve. To facilitate battery installation and replacement, the canister may include a body portion having a receiving opening sized to receive the battery and a resealable cap portion sized to cover and seal the receiving opening. The aperture may be formed in one of the body and cap portions.
The battery module is adapted for use with a battery-powered device such as a firearm aiming device that includes a housing having a battery-receiving cavity and a power input terminal assembly mounted to the housing within the battery-receiving cavity. The power input terminal includes a positive input terminal and a negative input terminal positioned to contact the respective conductive contact and canister of the battery module when the battery module is installed in the battery-powered device. One of the positive and negative input terminals preferably includes a resilient member or spring. A latching mechanism secures the battery module in the battery-receiving cavity and urges the battery module toward the power input terminal assembly to ensure that the supply of electric power from the battery to the power input terminals will not be interrupted during recoil of the firearm. The latching mechanism may comprise part of the battery-powered device, or may be formed in the cap portion of the canister.
In prior art battery compartments, flexible power input terminals can allow the battery to carom within the battery compartment, which may damage the battery, causing it to rupture and leak. In a preferred embodiment of the invention, the battery contacting end of the conductive contact extends into the interior of the canister and presses against the first battery terminal to secure the battery within the battery module. This arrangement restrains movement of the battery during recoil of the firearm and prevents damage to the battery. The seal may be sufficiently resilient to absorb all or part of the shock of recoil that would otherwise transfer to the battery and thereby provide further protection from damage induced by recoil.
In an alternative embodiment, the battery contacting end of the conductive contact extends into the interior of the canister so that the battery contacting end is positioned to form a gap between the battery contacting end and first battery terminal when the battery module is removed from the battery-powered device. The seal is preferably sufficiently resilient so that when the battery module is installed in the battery-powered device, part of the power input terminal assembly depresses the contact so that it presses against the first terminal of the battery. This feature prevents accidental battery discharge of the battery when the battery module is carried or stored outside of the battery-powered device. It also restrains movement of the battery within the canister during recoil of the firearm.
An additional advantage of the invention is it""s low cost of manufacture. Low manufacturing costs make it economical for the user to carry spare battery modules with batteries pre-installed.
Additional objects and advantages of this invention will be apparent from the following detailed description of preferred embodiments thereof which proceeds with reference to the accompanying drawings.